Process of making rouge



Patented F eb. .15, 1927.

UNITED STATES PATE PHILIP J. HESS, SR., OF KOKOMO, INDIANA, ASSIGNOR TO PITTSBURGH PLATE GLASS COMPANY, A CORPORATION OE PENNSYLVANIA.

PROCESS OF MAKING ROIIGE.

No Drawing. Original application filed October 30, 1919, serial No. 334,565, Patent No. 1,446,181, dated February 20, 1923. Divided and this application filed February 1, .1921. Serial No. 441,710.

The invention relates to the manufacture of polishing rouge such as that set forth in my Patent No. 1,446,181, issued Feb. 20, 1923, and of which application the present application constitutes a division. The invention has for its principal objects the provision of an improved process which will give a superior rouge and produce such rouge more quickly and economically than has heretofore been done.

In my process, as well as in those heretofore practiced for the production of rouge for polishing purposes, ferrous sulphate, commonly known as copperas, is employed.

The symbol for this material when in crystalline form is FeSO .7H O. The sugar form has also been very extensively employed, in which case the combined water is less.

The method of burning the copperas heretofore has varied considerably. In some cases it was customary for the operators to charge the furnace before quitting at night, leaving a low temperature in the furnace, whilegothers would charge in the morning with a comparatively warm furnace, from 600' to 900 F., the temperature being gradually raised and finally reaching 1600 to 1700 F. The charge was stirred at about thirty minute intervals and the-total period of burning was about ten hours. During the burning, the water of crystallization was driven from the copperas and the sulphate converted for themost part into ferric oxide or rouge, Fe O with the formation also of a variable percentage of basic ferric sulphate, 2Fe,O,5SO A variable percentage of the ferrous sulphate FeSO, also gen- .crally remained unconverted. As illustrative of the proportions of the above compounds produced by one characteristic calcining operation is the following:

Per cent.

, mo, 65 to 85 phate, and leaving only the ferric oxide. In

order to use the oxide thus produced, in polishing, it was necessary to mix it with water and add a solution containing ferrous 2Fe,'('),5s0, 10 to 30' sulphate (ordinarily referred to as acid), such solution being secured by passing steam or water through a mass of copperas. The addition of the solution of sulphate was vnecessary in order to secure a proper polishing action by the rouge,,the function of the solution of sulphate being to maintain the plasticity or stickiness of the rouge.

The amount of acid in the mixture was determined by a hydrometer. Care was taken .to avoid any excess'of the copperas solution because of its tendency to crystallize upon the polishing blocks and cause a marring or sleaking of the surface of the glass.

In other cases the mixture produced by the calcining operation was not washed, but

after the necessary amount of water for pollshing had been added, the acidity of the mixture as produced by the basic ferric ture contained as its acid content a substan-v tial amount of the ferrous sulphate (FeSO,,) solution, such acid content in the first instance being practically all ferrous sulphate solution and in the second case being made up partly of the sulphate solution and partly of the basic ferric sulphate solution.

I have found that the basic ferric sulphate is much more effective in its action as a com ponent of the rougepolishing mixture than the ferrous sulphate. Both compounds tend or plasticity to make it effective as a polisher, but the basic ferric sulphate gives greater friction and hence more polishing effect, and will not crystallize till the concentration is very great. The copperas solution, on the other hand, begins to crystallize very readily on concentration and such crystallization tends to form a crust at the edge of the polishing blocks and produce sleaking .or marring of the polished surface of the glass. The tendency ofthe mixture to mass or build up on the felts is much less with the ba'sioferric sulphate than with the copperas solution. My process'is therefore directed to the production of mixture in which the acid solution is substantially all to give the mixture the necessary stickiness provided by the use of the basic ferric sul phate, and in which the ferrous sulphate is cining or burning is to produce a product which contains a smaller proportion of the ferrous sulphate and a much higher proportion of the basic ferric sulphate. The calcining at a higher temperature and for a shorter period of time produces this result, a characteristic table of proportions being as follows:

Per cent. Fe O n 65 to 75 2Fe O 5SO, 25 to FeSO, .20

In the use of this material no copper-as water isadded, the basic ferric sulphate taktheplace of the copperas solution of the process, so that all that is necessary in the use of this material is to add the necessary amount of water,-the mixture being preferably muchthicker than that employed with the material produced by the old process. The basic ferric sulphate which goes into solution acts to maintain the plasticity of the mixture and gives it stickiness when used in the polishing operation, and the tendency of the mixture to mass or build up on the felts is reduced to a minimum, so that the mixture can be used throughout al most the entire polishing operation. About one pound of the polishing compound per four and a half gallons (4 of water has been found to ive the best results when the mixture is app ied according to my system,

butthis amount may be varied within'certain limits depending on the method of use without departing from the invention. A larger amount of rouge is applied during the first part of the operation than during the concluding portion, but the use of the felts with water alone continues for only a few minutes at the start of the operation.

lVith this mixture the total period of the polishing operation as-compared with the operation using the ordinary rouge mixture heretofore described is reduced about 30%, a substantial saving also being effected as to power, rouge and felt, although the power required per unit of time is greater than in the old operation, due to the greater friction produced by the use of the basic ferric sulphate.

In the calcining operation of my process the FeSO, is reduced to a minimum, which is desirable since its tendency is to crystallize as heretofore referred to, and thus produce marks or sleaks on the surface of the glass. The use of the basic ferric sulphate to produce the necessary plasticity and stickiness avoids this difficulty when used in the right proportion. I have found that the proportion above indicated produces the best results although a -somewhat lower as well as somewhat higher proportion may be employed. -VVhe'n the proportion ofbasic ferric sulphate becomes too hlgh, the sulphate may act as a'lubricant and thus retard polishing, and when the amount is too low the friction and consequently the polishing effect decreases.

The rouge as produced by my process appears tobe somewhat softer than that produced by the old processes, which may have something to do with the better results secured in polishing, but as heretofore stated, I believe that theadvantage is primarily due to the action of the basic ferric sulphate in maintaining the plasticity or stickiness of the rouge throughout the polishing operation, whereby the tendency of the material to thicken up or build up and to crystallize is avoided.

The reactions involved in carrying out my calcining operation are believed to be about as follows, the reactions set forth under occurring more or less concurrently:

If the heat were continued long enough the basic ferric sulphate would be converted into ferric oxide, but the heat is applied, as

heretofore stated, so as to'get the proper proportions of the oxide and sulphate. A small proportion of the FeSO (about twotenths per cent) remains undecomposed, as heretofore. indicated in the 'table showing the proportions of thecompounds after calcining. I I a in burning the copper-as, the oven is first broughtto high temperature, 1600 to 1700 F and the copperas'is then charged. The temperature then falls, 'due to the cooling etl'ect of the charge, to'about 900 to 1000 F., and the heating continues, the temperature reaching 1600? F. within two and onehalf hours. From this time; on the temperature is raised to.1700 to 1800 F. The whole calcining operation requires about four hours and the charge is stirred or' worked about three times during the entire calcination.

that substai'itially the same results may be obtained if the furnace ismaintained at a somewhat higher temperature,in which case, however, the time of burning should be decreased. By increasing the temperature the time of calcining may be reduced to the neighborhood of three hours. The time of burning may also run somewhat over four hours if the temperatures are employed below those stated. The time is also somewhat dependent upon the size of the charge,

the character of the furnace, and other conditions, so that the invention is not limited to the precise periods or teinperatures specilied heretofore.

What I claim is:

1. The process of preparing a polishing rouge mixture which consists. in heating ferrous sulphate until the water of crystallization is driven off and substantially all of the sulphate changed into a compoundco'mprising ferric oxide andbasic ferric sulphate, in the approximate proportion of two parts by weight of oxide to one of sulphate, and then mixing the compound with water in the approximate proportions of onepound of the compound per four and one half gallons of water.

2. The process of preparing polishing rouge mixture which consists in heating ferrous sulphate until the water of crystallization is driven off and substantially all of the sulphate changed into a compound comprising ferric oxide and basic ferric sulphate, and then mixing with water in the approximate proportions of 3.7 to 5.3 gallons of water per pound of compound.

3. The process of preparing a polishing rouge mixture which consists in charging ferrous sulphate into an oven heated to a temperature upward of 1400 F. and after such charging and consequent lowering of the temperature of the furnace, raising the temperature to upward of 1400 F., and then mixing the compound with water the total time of heating being between three and five hours, and the material being stirred at intervals.

4. The process of preparing a polishing rouge mixture which consists in charging ferrous sulphate into an oven heated to a temperature .of'1600 to 1700 F., and after such charging, bringing the temperature of the furnace up to 1700 to 1800 F., and then mixing the compound with water the total time of heating being approximately four hours.

In testimony whereof, I have hereunto subscribed my name this 26th day of J anuary, 1921.

PHILIP J., HESS, s". 

